Fruit and lung cancer.

Total fruit and lung cancer risk.

About the male analysis: In 2003 a pooled analysis of 8 prospective studies was published (Smith-Warner SA [24]). The analysis included data from a total of 1,808 men of which 298 were from The ATBC Study. In 2002 another publication about The ATBC Study included data from 1,644 men (Holick CN [18]), which is nearly as much as the total amount of cases from the pooled analysis. A similar finding was done with The Netherlands Cohort Study. For this systematic review it was chosen not to include data about men from the pooled analysis as a whole, but from the individual cohorts, because this allowed for a much larger amount of cases in the analysis.
As a consequence of this decision, data about men from The New York State Cohort (including 392 male cases) can not be included in these specific parts of the review, since no article is published about this specific cohort.

Results:

  • Men & women combined: 34 articles, providing information about 20 different cohorts were found, including 14,323 cases. Significant protective effects were found in 6 cohorts (Knekt P [8], Balder HF [11], Holick CN [18], Linseisen J [19], Neuhouser ML [22], George SM [29]), 2 of which were of very large size (19, 29). These 6 cohorts included 8.752 cases (61% of all cases). In addition, nonsignificant protective effects were found in a pooled analysis of 6 cohorts (Smith-Warner SA [24]), an in one additional cohort (Alavanja MC [27]), including another 1,445 cases (10% of all cases). No other (non)significant associations were found.
    The average RR = 0.85 (excluding incomplete data from Shekelle RB [1], Ratnasinghe D [15]).
  • Men: Data was provided about 11 cohorts including a total of 8,116 cases. A significant protective association was found in 4 cohorts (Knekt P [8], Balder HF [11], Holick CN [18], George SM [29]) including 7,300 cases (90% of all cases), and a nonsignificant protective effect was found in one other study (Shekelle RB [1]). No associations were found in the remaining 6 cohorts).
    The average RR = 0.87 (excluding incomplete data from Shekelle RB [1], Ratnasinghe D [15]).
  • Women: Data was provided about 9 cohorts including a total of 3,862 cases. A nonsignificant protective effect was found in a pooled analysis of 6 cohorts (Smith-Warner SA [24]), and a nonsignificant protective effect was found in one other cohort (Alavanja MC [27]) including 1,445 cases. No other associations were found, but all RRs were < 1.
    The average RR = 0.86
  • In 4 cohorts including a total of 2,345 cases, risk was not stratified by sex. Significant protective effects were found in 1 cohort (Linseisen J [19]), and in the placebo arm of another cohort (Neuhouser ML [22]), including 1,452 cases. No other associations were found. The average RR = 0.80

Inclusion of intermediate levels of consumption:
Though a fair amount of (non) significant associations were found, sometimes the trend, but not the effect (RR) was (non)significantly differend from 1.00.
(Non)significant effects at any level of consumption among men were as follows:

  • Knekt P (8) Significant at the highest tertile of consumption. This was defined as 106 g/day, but it is not clear if this was the median intake or the lower boundary from the range.
  • Balder HF (11) Significant at ≥ 88 g/day.
  • Holick CN (18) Significant at 127-188 g/day.

(Non)significant effects at any level of consumption among men were as follows:

  • Smith-Warner SA Significant at the 2nd-3rd quintile of consumption, and nonsignificant at the 5th quintile of consumption. No levels of consumption could be defined, because the pooled analysis included study-specific quintiles of consumption from the 6 cohorts.

A clear level of consumption for a protective effect is hard to define, because few RR's differed significantly from 1. But a protective effect may allready be found from consumption of ≥ 127 g/day.

The figure below includes effects from male and/or female cohorts with at least 500 lung cancer cases.



RRs for the association between total fruits and lung cancer risk among men and women (g/day).
Results from cohorts with ≥ 500 cases:


Effect modification by variables other than sex and smoking status:
No evidence of effect modification was found by age of diagnosis, or by the number of fruit and vegetable questions included on a study's FFQ (Smith-Warner SA [24]). And no evidence of effect modification was found by alcohol intake or multivitamin use (Feskanich D [14]).
But in one cohort, the protective effect of fruit was restricted to non-users of beta carotene/vitamin A supplements (Neuhouser ML [22]).

Conclusion: For men & women combined, significant protective effects were found in 6 cohorts, 2 of which were of very large size. These cohorts included a majority of the total amount of cases (61%), and no (non)significantly increased risks were found. The effect was of moderate size (- 15%). Total fruits consumption probably protects against lung cancer risk. Stratified by sex, total fruits consumption probably protects against lung cancer risk among men, while the evidence was only suggestive for a protective effect among women. But since the effect sizes were similar for men and women (- 13, and - 14%, respectively), no heterogeneity in effects seems to exist. The level of consumption for a protective effect is hard to define, but may allready be found at moderate consumption (≥ 127 g/day).

Prospective studies of total fruit and lung cancer risk (men):
AuthorCohort nameCasesRelative Risk (RR)
29) George SM (2008)The NIH-AARP Diet and Health Study4,092RR = 0.91 (0.81-1.01; P = 0.05)
27) Alavanja MC (2004)The Agricultural Health Study213OR = 0.9 (0.5-1.4; P = 0.64)
18) Holick CN (2002)The ATBC Study1,644RR = 0.87 (0.74-1.02; P = 0.01)
15) Ratnasinghe D (2000)No cohort name106No association (P = 0.49)
14) Feskanich D (2000)The Health Professionals' Follow-up Study258RR = 1.22 (0.87-1.87)
11) Balder HF (2005)The Netherlands Cohort Study1,426RR = 0.69 (0.53-0.91; P = 0.001)
8) Knekt P (1999)The Finnish Mobile Clinic Health Cohort138RR = 0.58 (0.37-0.93; P = 0.013)
5) Jansen MC (2004)The Zutphen Elderly Study42RR = 0.58 (0.26-1.29; P = 0.17)
4) Shibata A (1992)The Leisure World Study94RR = 0.99 (0.59-1.66)
2) Kvale G (1983)No cohort name70RO = 1.10 (P = 0.90)
1) Shekelle RB (1981)The Western Electric Study33An inverse association (P = 0.073)
Total number of cases: 8,116Average RR = 0.87


Prospective studies of total fruit and lung cancer risk (women):
AuthorCohort nameCasesRelative Risk (RR)
29) George SM (2008)The NIH-AARP Diet and Health Study2,347RR = 0.89 (0.77-1.02; P = 0.163)
27) Alavanja MC (2004)The Agricultural Health Study47OR = 0.6 (0.2-1.6; P = 0.09)
24) Smith-Warner SA (2003)Pooled analysis of 6 studies1,398RR = 0.83 (0.70-1.00; P = 0.07)
4) Shibata A (1992)The Leisure World Study70RR = 0.68 (0.37-1.24)
Total number of cases: 3,862Average RR = 0.86


Prospective studies of total fruit and lung cancer risk (not stratified by sex):
AuthorCohort nameCasesRelative Risk (RR)
25) Liu Y (2004)The JPHC Study428RR = 1.16 (0.84-1.58)
23) Takezaki T (2003)No cohort name defined51RR = 0.61 (0.29-1.30; P = 0.227)
22) Neuhouser ML (2003)The CARET Study326 (placebo), and

414 (intervention)
Placebo arm: RR = 0.56 (0.39-0.81; P = 0.003).
Intervention arm: RR = 0.79 (0.57-1.11; P = 0.13)
19) Linheisen J (2007)The EPIC Study1,126HR = 0.75 (0.59-0.96)
Total number of cases: 2,345Average RR = 0.80

Total fruit and lung cancer risk. Stratified by smoking status.

Background:
About the analysis: For this systematic review, data is stratified by smoking status into current smokers, former smokers, and never smokers.
The JPHC Study (Liu Y [25]) and CARET Study (Neuhouser M [22]) provided data about "ever smokers" without stratifying into former vs current smokers. Likewise, The Finnish Mobile clinic Health Cohort (Knekt P [8]) provided data about "current nonsmokers" without stratifying into nonsmokers vs former smokers. It was chosen not to include this data in the following tables.
About the analysis of current smokers: In 2003 a pooled analysis of 8 prospective studies was published (Smith-Warner SA [24]). The analysis included data from a total of 1,915 smoking cases of which 298 were from The ATBC Study. In 2002 another publication about The ATBC Study included data from 1,644 smoking cases (Holick CN [18]), which is nearly as much as the total amount of cases from the pooled analysis. For the systematic review it was chosen not to include data about current smokers from the pooled analysis as a whole, but from the individual cohorts, because this allowed for a much larger amount of cases in the analysis.

Results:

  • Current smokers: Data about current smokers was provided by 8 cohorts, including 6,251 cases. Significant protective effects were found in 3 cohorts of moderate-very large size, including 2,943 cases (47% of all cases). No other (non)significant associations were found. The average RR = 0.86
  • Former smokers: Data about former smokers was provided by a pooled analysis of 7 cohorts, and 2 additional cohorts. No (non)significant associations were found, but all RR's were < 1. The average RR = 0.90
  • Never smokers: Data about never smokers was provided by a pooled analysis of 7 cohorts, and 3 additional cohorts. No (non)significant associations were found. The average RR = 0.94

Conclusion: Among current smokers, significant protective effects were found in 3 cohorts, including 47% of all cases. Suggestive evidence was found for a protective effect of total fruits against lung cancer risk among current smokers (- 14%). No evidence was found for an association among former or never smokers.

Prospective studies of total fruit and lung cancer risk (current smokers):
AuthorCohort nameCasesRelative Risk (RR)
29) Wright ME (2008)The NIH-AARP Diet and Health Study1,583 men, and
1,196 women
Men: RR = 0.84 (0.69-1.04; P = 0.12).
Women: RR = 0.95 (0.78-1.17; P = 0.58).
19) Linseisen J (2007)The EPIC Study731HR = 0.72 (0.52-0.99)
18) Holick CN (2002)The ATBC Study1,644RR = 0.87 (0.74-1.02; P = 0.01).
14) Feskanich D (2000)The Health Profesional's Follow-up Study

&

The Nurses' Health Study
86 men, and

269 women
Men: 1.54 (0.76-3.13).
Women: RR = 0.89 (0.59-1.35).
11) Voorrips LE (2000)The Netherlands Cohort Study568RR = 0.7 (0.4-1.0; P = < 0.0001).
10) Steinmetz KA (1993)The Iowa Women's Health Study81OR = 0.95 (0.46-1.96; P = 0.7).
8) Knekt P (1991)The Finnish Mobile Clinic Health Cohort93RR = 0.98 (P = 0.89) for low vs high consumption.
Total number of cases: 6,251Average RR = 0.86


Prospective studies of total fruit and lung cancer risk (former smokers):
AuthorCohort nameCasesRelative Risk (RR)
29) Wright ME (2008)The NIH-AARP Diet and Health Study2,110 men, and
835 women
Men: RR = 0.91 (0.79-1.05; P = 0.36).
Women: RR = 0.94 (0.75-1.17; P = 0.85).
24) Smith-Warner SA (2003)Pooled analysis of 7 studies981RR = 0.85 (0.69-1.05; P = 0.43)
19) Linseisen J (2007)The EPIC Study291HR = 0.93 (0.59-1.48)
Total number of cases: 4,217Average RR = 0.90


Prospective studies of total fruit and lung cancer risk (never smokers):
AuthorCohort nameCasesRelative Risk (RR)
29) Wright ME (2008)The NIH-AARP Diet and Health Study141 men, and
170 women
Men: RR = 0.81 (0.46-1.41; P = 0.35).
Women: RR = 1.08 (0.64-1.84; P = 0.99).
25) Liu Y (2004)The JPHC Study106RR = 2.09 (0.56-7.83; P = 0.22)
24) Smith-Warner SA (2003)Pooled analysis of 7 studies259RR = 0.59 (0.34-1.04; P = 0.16)
19) Linseisen J (2007)The EPIC Study98HR = 0.59 (0.25-1.38)
Total number of cases: 774Average RR = 0.94

Total fruit and lung cancer mortality.

11 articles, providing information about 9 different cohorts were found. The dietary assessement was conducted following cancer diagnosis, in one cohort only (Skuladottir H [19]).

Results:

  • Men: Data was provided about 7 cohorts including 4,057 cases. Significant protective effects were found in 5 cohorts (Wang LD [3], Jansen MC [5], Ozasa K [17], Appleby PN [20], Sauvaget C [21]) including 3,797 cases (94% of all cases). RRs were well below 1 in both remaining cohorts.
    Risk was often presented in frequency of consumption (times or days/week: 3, 9, 17, 20, 21). And significant protective effects were found at (almost) daily consumption in 4 of these cohorts (3, 17, 20, 21). The average RR = 0.60
  • Women: Data was provided about 3 cohorts. No (non)significant effects were found, but RRs were < 1.
  • Two other cohorts did not stratify risk by sex. No significant effects were found, but RRs were < 1.

Conclusion: Significant protective effects were found in 5 cohorts - one of which of very large size. These 5 cohorts included a total of 84% of all cases. In addition, all RRs were below 1.
Total fruit probably protects against lung cancer mortality. Stratified by sex, (almost) daily consumption of total fruits probably protects against lung cancer mortality among men (- 40%), while no associations were found among women.

Prospective studies of total fruit and lung cancer mortality (men):
AuthorCohort nameCasesRelative Risk (RR)
26) Khan MM (2004)No cohort name41RR = 0.8 (0.3-2.2)
21) Sauvaget C (2003)The Hiroshima/Nagasaki Life Span Study345A significant protective effect (RR = 0.68)
20) Appleby PN (2002)The Health Food Shoppers Study51RR = 0.47 (0.27-0.84; P = < 0.05)
17) Ozasa K (2001)The JACC Study300HR = 0.73 (0.55-0.97; P = 0.049)
9) Chow WH (1992)The Lutheran Brotherhood Study219RR = 0.7 (0.4-1.3)
5) Jansen MC (2001)The Seven Countries Study149RR = 0.69 (0.46-1.02; P = 0.05)
3) Wang LD (1985)No cohort name2,952MR = 1.75 for low vs high consumption.
Total number of cases: 4,057Average RR = 0.60


Prospective studies of total fruit and lung cancer mortality (women):
AuthorCohort nameCasesRelative Risk (RR)
21) Sauvaget C (2003)The Hiroshima/Nagasaki Life Span Study175No association
20) Appleby PN (2002)The Health Food Shoppers Study30RR = 0.65 (0.31-1.35)
17) Ozasa K (2001)The JACC Study84HR = 0.80 (0.42-1.50; P = 0.66)
Total number of cases: 289


Prospective studies of total fruit and lung cancer mortality (not stratified by sex):
AuthorCohort nameCasesRelative Risk (RR)
19) Skuladottir H (2006)The Danish Diet, Cancer and Health StudyNot definedA nonsignificant protective effect: HR = 0.81 (0.58-1.15)
16) Breslow RA (2000)The NHIS154RR = 0.9 (0.5-1.6; P = 0.489)
Total number of cases: 154 + X